Dear Sir .
Please help me to correct this error
Line:40
char:11
Error:'lenght' is null or not an object
Code:0

I got this great script from>>
/***********************************************
* JavaScriptKit.com Multiple Choice Quiz Script (http://www.javascriptkit.com)
* Copyright 2003 JavaScript Kit- http://www.javascriptkit.com
* This notice and footnote must stay intact for use
* Visit JavaScript Kit (http://www.javascriptkit.com/) for full source code
***********************************************/
But when I changed the number to 20 ,There an error ,the script doesn't work